You've got your new computer up and running. You've waited a couple of months. You're sure there's nothing else you want on your old PC. So what do you do with that big gray box in the closet?

Destroy the Evidence

First, you have to make sure there's nothing on the hard drive that could be used against you. I'm not just talking about illicit love letters or shady business deals; you don't want anything with a credit card or Social Security number falling into the wrong hands.

Deleting files or formatting hard drives isn't good enough. The data may still be on the drive, where anyone with moderate technical abilities can retrieve it. You need to wipe the data--write over the physical clusters--to make sure it's gone.

Start by asking yourself two questions:

The first is "Do I want to wipe the entire drive or just select files and folders?" Wiping the drive is easier (you don't have to decide what to delete), but someone will have to reinstall Windows, drivers, and so on afterwards.

The second is "How paranoid am I?" There are plenty of free programs that will wipe your data so that it cannot be recovered by anyone other than a very skilled professional using very expensive, specialized hardware. For most people, that free software is good enough. But if you think the FBI is after you, you'll want to spend some money for more security.

If you want to wipe files and folders with a reasonable degree of security, I recommend Summit Computer's free Hard Disk Scrubber 2. But if you're truly paranoid, go with Jetico's $40 BCWipe.

If you decide to wipe the whole disk, use LSoft's Active@ KillDisk. The free version is good enough for most people; secret agents should buy the $30 Professional version.

Bad Ideas

Once you've wiped the hard drive, what do you do with the old PC? There are plenty of possibilities, most of them not worth doing. Here are a few to avoid:

Sell It. Computers drop in value quicker than anything except milk. Whatever you get for it won't be worth the hassle.

Turn It Into a Print Server. Yes, you can hook up the old PC to your network, plug the printer into it, and leave it on all of the time so that other computers can print through it. But it's big, bulky, and sucks power. It's easier to plug the printer into one of the computers already on your network, and leave that PC on 24/7.

Throw It Away. There are too many computers in landfills already, and there's material in a PC that you don't want in your groundwater. Finally, there is someone in the world who could use your computer.

The Gift That Keeps on Computing

The best possible way to get rid of an old PC is to give it away. But to whom?

How about a loved one? Is there anyone in your family who needs a computer? Or a better one? Remember, your outdated model is another person's upgrade.

But there's a caveat: If you give your computer to someone you're close to, you will become the recipient's technical support specialist. In other words, they'll feel free to call you with all their questions.

That's not a problem if you donate your old machine to a school or a charity. Call your local school or school district and ask if they're interested. Most likely you'll get transferred to someone who knows enough to ask intelligent questions. Of course, after asking those questions, they might just turn you down. Many schools don't want a computer unless it is in working condition, comes with a legitimate copy of Windows (they don't want to run afoul of Microsoft), and are not too old.

If you read this article before Labor Day, you can take that PC or any other technology gear you no longer need to any Office Depot, which will recycle it for you for free (one item per person, per day). That program ends September 6. Go to Office Depot's Web site for more information.

Finally, TechSoup maintains an online database of charities and businesses that can take your old computer off your hands. You can search by zip code to find local organizations that will get a working computer someplace where it can do some good, refurbish a nonworking computer, or recycle the materials in a PC that's beyond refurbishing. And be sure to get a receipt: A donated computer is a tax deduction.

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